qubit_argument/argument/
option_argument.rs

1// =============================================================================
2//    Copyright (c) 2025 - 2026 Haixing Hu.
3//
4//    SPDX-License-Identifier: Apache-2.0
5//
6//    Licensed under the Apache License, Version 2.0.
7// =============================================================================
8//! Ownership-preserving validation for optional arguments.
9
10use crate::argument::{
11    ArgumentError,
12    ArgumentErrorKind,
13    ArgumentResult,
14    sealed::Sealed,
15};
16
17/// Validates optional arguments without requiring their values to be cloned.
18///
19/// A required value can be extracted with [`Self::require_some`]. Conditional
20/// validation borrows a present value only for the validator call and returns
21/// the original option on success.
22///
23/// The trait is sealed and implemented only for `Option<T>`.
24pub trait OptionArgument<T>: Sealed + Sized {
25    /// Requires this option to contain a value.
26    ///
27    /// A present value is moved out and returned without cloning. An absent
28    /// value returns [`ArgumentErrorKind::Missing`] at `path`.
29    fn require_some(self, path: &str) -> ArgumentResult<T>;
30
31    /// Validates a present value by temporary borrow.
32    ///
33    /// `validator` receives a shared reference when this option is present. A
34    /// successful validator returns the original option without cloning its
35    /// value; it introduces no failure kind of its own and propagates any
36    /// [`ArgumentErrorKind`] returned by `validator` unchanged. An absent
37    /// option is returned without executing `validator`.
38    fn validate_if_some<F>(self, validator: F) -> ArgumentResult<Self>
39    where
40        F: FnOnce(&T) -> ArgumentResult<()>;
41}
42
43impl<T> OptionArgument<T> for Option<T> {
44    /// Extracts a present value or reports that `path` is missing.
45    ///
46    /// The contained value is moved without cloning. An absent option returns
47    /// [`ArgumentErrorKind::Missing`].
48    #[inline]
49    fn require_some(self, path: &str) -> ArgumentResult<T> {
50        match self {
51            Some(value) => Ok(value),
52            None => Err(ArgumentError::new(path, ArgumentErrorKind::Missing)),
53        }
54    }
55
56    /// Borrows and validates a present value, then returns the original option.
57    ///
58    /// A validator error is returned unchanged. When this option is absent,
59    /// `validator` is not executed.
60    #[inline]
61    fn validate_if_some<F>(self, validator: F) -> ArgumentResult<Self>
62    where
63        F: FnOnce(&T) -> ArgumentResult<()>,
64    {
65        if let Some(value) = self.as_ref() {
66            validator(value)?;
67        }
68        Ok(self)
69    }
70}
qubit_argument/argument/option_argument.rs

qubit_argument/argument/
option_argument.rs
